Help with hot water heating system

branimal

I have a heating / cooling system - I don't know exactly what it's called. Basically the unit has hot water pipes pumping through them and the heating / cooling systemhas a blower that blows on the pipes and directs heat into the home.

It also has an Air conditioning unit in it.

I have four of these units located throughout my condo. 2 of the units upstairs are working fine. The 2 units downstairs are blowing cold air.

When I first bought the condo, I had a heating issue and the super bled the lines on the unit. It was working fine after that.

The condo is now a rental unit and I need to get the heat back on for my tenants.

Can anyone tell me
a) what kind of unit this is (maybe I can google some DIY tips)
b) how I can go about bleeding it

I know this is a vague description, but I'm not on site, so I can't take pictures and provide a more detailed description until I get there.

JUGHNE

Perhaps a hydro air set up.
What heats the water?
How many wall thermostats are there?

Jamie Hall

It's called a hydro-air system, and they work pretty well... but, it may need to be bled (again) as air in the water side of the coils will defeat them. So, however, will having a valve closed. Is there a thermostatic valve on these things?

branimal

The water is heated by a single common gas boiler in the basement.

Here are the heat controls:

branimal

I recall the super bled them using plastic tubing connected to a bucket and small screwdriver to open the release nozzle. All the air blew out and then he closed the nozzle when the hot water started coming out.

We no longer have a super, so I’ve got to do it myself.

Jamie Hall

You can try bleeding them just as the super did -- it's not rocket science and worth a try. Those units operate, though, sort of in two stages: when the thermostat calls for heat, if the pushbutton for heat is selected the fan should turn on and a valve should open to allow hot water to circulate. You may have to take some covers off to check and see if the valve is opening.

branimal

So is it just a matter of opening the bleed valve and letting it run? No need to turn and knobs?

Thanks

Jamie Hall

branimal said:

So is it just a matter of opening the bleed valve and letting it run? No need to turn and knobs?



Thanks

so far as bleeding goes, that should be it. No need to let a whole lot of water out, though -- you're just trying to get rid of the air.

Intplm.

@branimal
I agree with @Jamie Hall here but be careful of the type of purge that is provided.
Sometime the purges can have very flimsy flexible copper tubing attached to a knurled thumb screw or flat screwdriver purge head.
They can break. So, you might need to use two hands.

And purge a lot. The amount of water needed to pass through the coil is always more then one would expect.

branimal

I found what I believe to be the bleed nipple. First I started working it off with channel locks, but water was coming past the threads.

Seems to be a flat head screw on the face of that bleed port. Such a tight space I can’t really tell.

Also next to the heater is a metal access door with shutoff valves. All the pipes there are hot.


How do I go about bleeding this?

STEVEusaPA

-Make sure the system is off before bleeding.
-Make sure you keep the pressure up in the system.

That silver box looks like a zone valve. You should see a lever where you can manually open it. If it is a zone valve, turn on the system and see if it is opening. If not, you can manually open it. If hot water circulates, it's the zone valve.

branimal

I closed the valve with the bleed nipple attached and unscrews the nipple. Connected a hose to a bucket and drained 2 buckets worth. Black hot water came out. Once the bucket was full I shut off the valve and restarted the system. The pipe with the bleed nipple is hot and the return pipe is cold. I’m still blowing cold air.


One variation of this is to bleed the system as above but close the return lines shut off valve.


I’m assuming both incoming and outgoing valves should be open when running the system. Not sure on the valve oreientatjon when bleeding the system.

Nothing in that zone valve box to switch on or off.

Alan Welch

Think it's a zone valve replacement time.Thr Taco zone sentry valves are a good replacement, easy to diagnose as well.

JUGHNE

It unusual for 2 units to quit at the same time.
Somewhere is a 120/24 volt transformer for these valves.
Could be in the unit. One wire looks pinched in the cover, could have shorted out the transformer.

What tells the boiler to turn on?

branimal

The boiler is turned on manually. Other people on the same floor have heat. 2/4 of my heaters are working. And I can feel the feeder pipes are hot. If the heat wasn’t working for others, the buildings email threads would be flaming.

The incoming pipe gets hot when I bleed it. Up to a certain point. Maybe 12” past the bleed port. The remaining pipe leading to the return pipe are cold. Hence it’s blowing cold air.

mattmia2

That little slot in the zone valve cover would have the manual opener lever. I'm not sure if it is a model without a manual lever or if it it broken off. If 2 are not heating it is probably the control, not the valve itself (unless one wasn't heating and 3 were enough so no one noticed it). It is time to get the voltmeter and see if you have 24vac to the zone valve and work from there.

JUGHNE

Does each unit have isolation ball valves?
That would make the changing much simpler.
I wonder if these zone valves were added as an after thought, not original to the system.

Some valves allow you to remove the motor for changing and this would let you open them manually. However with some you have to take the pressure off and all the guts come out.

One picture looks like there is a lever inside on the bottom behind the motor, could be the manual override.

mattmia2

It looks like you can see isolation valves in one of the pictures. I'd close them and open the bleeder to make sure they are holding before unscrewing the motor for the zone valve, but since 2 don't work i'd look for 24vac at the motor first.

Alan Welch

I would close both valves and replace the bleeder after relieving pressure Then open the valve under the zone valve and see if you get a good flow from the bleeder . If you only get water with the other valve open the zone valve is closed and is your problem. Where you had water from the bleeder before I don't think air is your problem. Where is this located?

branimal

Each unit has two shutoff or isolation valves.

Will write more later, but is there a way I can just bypass the zone valve? Like hot wire it? The units are typically turned on and off as needed.

I’m located in NYC.

branimal

Ok I'm finally in front of a laptop and can write in normal sentences.

Each of the 4 hydronic units has their own thermostat - the knob on the control panel. See pic.

There is no other thermostat in the condo unit.

Each of the 4 hydronic units has their own set of shut off valves.

2 out of 4 units are not working.

I read up a little on zone valves last night and have a basic understanding why either the wiring on the zone valves have gone wonky or the zone valves themselves are faulty.

2 zone valves going bad at the same time seems strange. But possible.

It could be the wiring. I have a Harbor Freight multimeter (I know it's crap)

@mattmia2 & @JUGHNE - how do I use the multimeter to check for 24vac at the zone valve / motor? And what do I do if there isn't 24vac at the zone valve motor?

I think kind of have a fuzzy idea of how the wiring works;
1. 240 volt power comes into the unit.
2. Transformer steps down the power to the thermostat (knob control panel)
3. Thermostat sends on/off signal to the zone valve via opening or closing the motor.

Is there a way to hot wire it open for now?

How can I manually override the zone valve? One zone valve appears to have the override lever broken. Maybe I can remove the cover and slide over the control with a flathead screwdriver. Will it stay in that position if I leave it like that? The tenant typically shuts the units off with the standby switch.

The other zone valve might have the controls on the bottom of the valve. Perhaps the installer installed it upside down.


Also, just want to verify, the zone valves attaches to the return pipe correct? I didn't take too close a look, b/c I was too focused on bleeding the lines.

Is this logic correct: If the zone valve closes the return line then no hot water can get into the heater coils. When I'm bleeding the system a short length of the incoming copper pipe gets hot b/c some of the cold water is being displaced by hot water. But the main length of coil remains cold.

Jamie Hall

You certainly have the right ideas. Those things require a fair amount of ingenuity to test and repair.

I notice one of the ball valves for unit 2 appears to be closed? That's deliberate, I presume?

branimal

Jamie Hall said:

You certainly have the right ideas. Those things require a fair amount of ingenuity to test and repair.

I notice one of the ball valves for unit 2 appears to be closed? That's deliberate, I presume?

Ball valve was closed so i could remove the bleed nipple and attach my tubing to bleed the unit.

branimal

If I can't figure how to fix this elegantly - Can I go the ballistic route?

Shut off both ball valves, cut the section of copper pipe attached to the zone valve, replace with straight pipe and call it a day.

The tenants typically turns the heater on and off based on their needs. I feel like that thermostat never really worked anyway. Probably b/c that zone valve or the thermostat is wonky.

mattmia2

The thermostat probably doesn't work so well because it is right where the heat source is. They would all work better if they had a single t-stat on an interior wall somewhere in the middle of the room controlling them all. T-stat wire could be run under/along the baseboard to get there. But that is a side note.

The zone valve lever will move over and lock in that little notch in the slot, so if you open it manually with something you need to find something to wedge in it to hold it open if it isn't sticking out of that slot (it could be a version without the manual opener as well). I think you can take the motor off that valve and open it by hand, I think it is sealed separately from the motor. You might need to find a way to hold the valve stem open. Others will know the exact internals of that valve, I have only worked with a honewell version of that valve.

The 2 wires to the zone valve motor should have 24 vac across them if you measure with the meter set to ac volts at an appropriate range across the 2 wires(probably 200 vac). If you don't see 24 or so vac you need to figure out where the transformer is feeding the t-stat and valves and look for 24 vac out of it, if the xfmer is ok, bypass the tstat with a jumper and see if the valve opens.

The system is under pressure so if either of the isolation valves is open water will flow out through the bleeder (if the zone valve is open, if the zone valve is closed it won't flow from that side out the bleeder). The system pressure will make water flow the wrong way through the return and out the bleeder if that is the only path from the system.

JUGHNE

If the zone valves are locked open, the water will flow constantly and maybe overheat on mild days. The Tstat would still operate the fan. You could throttle the flow down with the ball valves but finding the sweet spot may be tough.

I would check for the 24 volts first.

branimal

@mattmia2

> The zone valve lever will move over and lock in that little notch in the slot, so if you open it manually with something you need to find something to wedge in it to hold it open if it isn't sticking out of that slot (it could be a version without the manual opener as well). I think you can take the motor off that valve and open it by hand, I think it is sealed separately from the motor. You might need to find a way to hold the valve stem open. Others will know the exact internals of that valve, I have only worked with a honewell version of that valve.
>
Packing my toolbags now. What can be used to jam the zone valve lever in place?

mattmia2

I think those valves use torx screws so make sure you have a torx driver.

branimal

Before I did anything I felt the pipes. Cold.

Pull the motor off. Both pipes instantly got hot.

The I turned the toggle and it seems to have gotten even hotter. I zipped tied them in place.

Going to grab some lunch and see if everything is fine when I get back.

branimal

Oh I tried using the multimeter but I’m not sure I understand all the settings. It read zero in this configuration.

mattmia2

assuming the meter is working, you should have seen about 24 v at the motor with the meter set that way

branimal

As soon as I pulled the motor off I could instantly feel all pipes get hot. I guess the motor on the zone valve kept the valve closed. Is the valve a binary valve. Just on or off?

Or does throttling that lever in the open direction widen the opening for hot water to flow to the coils? Forgot to bring my heat gun to measure the surface heat.

Perhaps the tenants will feel the apartment is too hot on mild days, but b/c the tenants would turn off the blowers the heat shouldn't disseminate too badly around the room. Fingers crossed.

The building is a 14 unit condo with shared boiler. The boiler gets turned on and off once certain temperatures are hit. On in October and off in April or May.

I realize that having the valve wide open is wasting energy. Hot water is flowing constantly through those coils, when in should only be flowing when the system / user calls for heat.

Regarding the 24VAC being fed to the motor: I put the multimeter up to the two wires coming from the unit feeding the zone valve's motor. It read zero. Then I think I uncovered both wire-nuts and tested the bare wires - no reading.

So I guess there is an an issue with the transformer.

But how could two different transformers get blown out?

branimal

Forgot to thank everyone here for helping me through this!! I know I only have a temporary solution but my tenant's are warm during an unusually cold spell here in NYC.

Thank you!!!!

JUGHNE

I don't know what that device is. If you follow those wire you may find one transformer that does both units.
I think it is possible that these coils were always hot and temp controlled by the tstat running the fan. The zone valves were added later perhaps. You could throttle the ball valves down for less flow and perhaps the fan control would keep the temp fairly consistant.